<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
  <form action="">
    <input type="file" name="" id="file">
    <input type="submit">
  </form>
  <script>
    var file = document.getElementById('file')
    file.onchange = function() {
      console.log(this.files[0])//获取文件信息
    }
  </script>
</body>
</html>